Synthesis and use of well-defined, highly-branched saturated hydrocarbon polymers

ABSTRACT

The present invention relates to a method to produce highly branched polymers with a polyolefin backbone structure of ethylene and precise control of the nature of the branching. In particular, the distribution of branch length and number of branches can be more precisely controlled via the polymerization method of the present invention. The method comprises using anionic chemistry to make unsaturated polydienes with a well-defined, highly-branched structure, and then hydrogenating these polydienes to form highly branched or dendritic saturated hydrocarbon polymers. Highly branched or dendritic polyethylene, ethylene-propylene copolymer and atactic polypropylene are among the saturated hydrocarbon polymers that can be anionically synthesized via the proper selection of diene monomer type, coupling agent, and hydrogenation conditions. These polymers find application in injection molding and extrusion processes as a minor additive for improving processability of linear polyolefins by delaying the onset of melt fracture, and correspondingly increasing melt throughput rates.

FIELD OF THE INVENTION

The present invention relates to the field of highly branchedhydrocarbon polymers. It more particularly relates to an improvedcomposition and method of preparing hyperbranched or dendritic saturatedhydrocarbon polymers using anionic polymerization followed bysaturation. Still more particularly,-the present invention relates tocompositions and method of preparing highly-branched saturatedhydrocarbon polymers with a more precise placement of the chain branchesand a narrower distribution of both chain branch length and number ofchain branches.

BACKGROUND

High pressure low density polyethylene (HP-LDPE) is a complicatedmixture of highly branched polymers with a very broad molecular weightand structural polydispersity that is nearly impossible to characterize.It was the first form of polyethylene (PE) to become commercially viableand was discovered in 1933. The basic process is the free radicalpolymerization of supercritical ethylene. Typically this means that thereactions are done at high pressure (over 150 MPa) and temperatures of150 to 350° C. Some sort of free radical initiator is needed for thesereactions, for example, oxygen or peroxides are commonly employed. Twomain types of reactors are used—autoclaves and tubular. The polymersmade in this process are characterized as having a highly branchedstructure. This is believed to come about from two main mechanisms.

In one mechanism, the free radical on the growing end of a chain canloop back (mainly five carbon loops) to some other portion of the chain.The loop breaks at the point of reaction, to which the radical istransferred. The loop then becomes a branch off of the chain, whichcontinues to grow from the reaction point as depicted in prior artFIG. 1. This backbiting reaction mainly leads to short branches a fewrepeat units long (especially butyl branches). Much longer branches areproduced from the second mechanism, in which the growing end of a chainterminates on another molecule as depicted in prior art FIG. 2. Severalother mechanisms have also been proposed, and the complete suite ofreactions that occur has not been firmly elucidated. It is clear though,that these mechanisms result in a very complicated, tree-likearchitecture with both short and long chain branches. These are called‘low-density’ polyethylenes (LDPE) in contrast to the higher density,linear versions. The reason that the products of the high pressureprocess have lower density is that they are lower in crystallinity. Onlylong methylene sequences can participate in the paraffin-like crystalsof PE, so the side branches serve to lower the crystallizability ofLDPE. This effect is mainly due to the short branches (e. g., ethyl,butyl, hexyl) that arise from the backbiting mechanism, simply becausethere are many more of these. Since the frequency of such branching canbe controlled by various process variables (Temperature, Pressure,initiators), so can the density or crystallinity of the polymers.

The lower density structures yield polymers that work well in manyextrusion processes. The power needed to extrude the polymer through adie and blow film, for instance, in much less than that for acorresponding linear polymer, however there are poorer mechanicalproperties (for example tear strength and dart impact) compared tolinear polymers. This is due to the long chain branching (LCB) of theHP-LDPE, and more precisely to the nature of the LCB in it, that is, thelength, number, and placement of the branches in each molecule, and thedistribution of these parameters among the chains. Moreover, the bubblethat forms when the film is formed is more stable to rupture withHP-LDPE than LLDPE, allowing higher throughout rates. On the other hand,the mechanical properties of LLDPE films, such as tear strength and dartimpact strength, are much greater than for HP-LDPE. To get a balance ofboth processability and film performance, many film manufacturers useblends of HP-LDPE and LLDPE, but these are clearly still far from theoptimum that might be obtained.

U.S. Pat. No. 6,255,424 discloses a convergent method for makingdendritic polymer structures via a single step (one pot), anionicpolymerization process in a living polymer system. More particularly, amethod is disclosed for making vinyl-containing dendritic polymerstructures. The method yields a broad distribution of the number ofbranches and their corresponding length.

A need exists for an improved composition and synthesis method ofproducing highly branched saturated hydrocarbon polymers with improvedcontrol of the branch length, branch number and placement of the longchain branching (LCB parameters),such that the resulting polymer willhave both superior processing and mechanical performance. Moreparticularly, a need exists to prepare model comb polyethylenes withone, two, or more linear branches, using anionic polymerization ofbutadiene and controlled linking chemistry, followed by hydrogenation asdisclosed in U.S. Pat. Nos. 6,355,757, 6,391,998, and 6,417,281, all ofwhich are herein incorporated by reference. Still more particularly, aneed exists for a synthesis method that yields well-defined branchedsaturated hydrocarbon polymer compositions, which have either brancheson branches or tetrafunctional branched products.

SUMMARY OF THE INVENTION

According to the present disclosure, an advantageous convergent methodfor anionically synthesizing a highly branched well-defined 1^(st)generation polydiene comprises the steps of 1) reacting a diene monomer(d) with sec-BuLi to form a single double-tailed macromonomer of(Pdd₁)⁻Li⁺, 2) coupling two of said single double-tailed macromonomersof (Pdd₁)⁻Li⁺ together in a convergent manner by reacting with dichloromethyl silane diphenylethylene (DCMSDPE) coupling agent to form a doublemacromonomer of polydiene with a middle active center, 3) reacting saiddouble macromonomer of polydiene with said diene monomer and sec-BuLi atthe middle active center to form a 1^(st) generation-diene-lithiumbranch on branch structure, and 4) combining three or more of said1^(st) generation-diene-lithium branch on branch structures by reactingwith trichloro silane coupling agent to form highly branchedwell-defined 1^(st) generation polydiene.

A further aspect of the present disclosure relates to an advantageousconvergent method for anionically synthesizing a highly branchedwell-defined 2nd generation polydiene comprising the steps of 1)reacting diene monomer (d) with sec-BuLi to form a single double-tailedmacromonomer of (Pdd₁)⁻Li⁺, 2) coupling two of said single double-tailedmacromonomers of (Pdd₁)⁻Li⁺ together in a convergent manner by reactingwith dichloro methyl silane diphenylethylene (DCMSDPE) coupling agent toform a double macromonomer of polydiene with a middle active center, 3)reacting said double macromonomer of polydiene with said diene monomerand sec-BuLi at the middle active center to form a 1^(st)generation-diene-lithium branch on branch structure, and 4) reactingsaid 1^(st) generation-diene-lithium branch on branch structures withDCMCDPE coupling agent followed by the further addition of said singledouble-tailed macromonomer of (Pdd₁)⁻Li⁺ to form a highly branchedwell-defined 2nd generation polydiene.

Another aspect of the present disclosure relates to an advantageousconvergent method for anionically synthesizing a double-comb polydienecomprising the steps of 1) reacting diene monomer (d) with sec-BuLi toform a single double-tailed macromonomer of (Pdd₁)⁻Li⁺, 2) coupling twoof said single double-tailed macromonomers of (Pdd₁)⁻Li⁺ together in aconvergent manner by reacting with styryl silane coupling agent to forma double macromonomer of polydiene with a middle active center, 3)reacting said double macromonomer of polydiene with said diene monomer,sec-BuLi and potassium 2,3-dimethyl-pentoxide-3 (R—O⁻K⁺) to form adouble-comb diene-lithium branch structure, and 4) combining three ormore of said double-comb diene-lithium branch structures by reactingwith trichloro silane coupling agent to form a double-comb polydiene.

Numerous advantages result from the advantageous composition, use andmethod of preparing hyperbranched or dendritic saturated hydrocarbonpolymers using anionic polymerization disclosed herein and theuses/applications therefore.

For example, in exemplary embodiments of the present disclosure, thedisclosed hyperbranched or dendritic saturated hydrocarbon polymersprovide for a narrower distribution of chain branches and more preciseplacement of chain branch location.

In a further exemplary embodiment of the present disclosure, thedisclosed hyperbranched or dendritic saturated hydrocarbon polymersallow for various branch structure including double-comb,3-arm-double-comb star, and double molecular brushes.

In a further exemplary embodiment of the present disclosure, thedisclosed hyperbranched or dendritic saturated hydrocarbon polymers whenblended in minor amounts with LLDPE, HDPE, and HMW-HDPE, improveprocessability by delaying the onset of melt fracture whichcorrespondingly improves melt output rates in extrusion and injectionmolding operations.

In a further exemplary embodiment of the present disclosure, thedisclosed hyperbranched or dendritic saturated hydrocarbon polymers whenblended in minor amounts with LLDPE, HDPE, and HMW-HDPE, do notnegatively effect mechanical properties such as tear strength and dartimpact resistance.

In a further exemplary embodiment of the present disclosure, thedisclosed hyperbranched or dendritic saturated hydrocarbon polymers whenblended in minor amounts with LLDPE, HDPE, and HNW-HDPE, areparticularly useful in forming film, sheet, pipe, fiber and otherextruded articles.

In a further exemplary embodiment of the present disclosure, thedisclosed hyperbranched or dendritic saturated hydrocarbon polymers maycomprise LDPE, ethylene-propylene copolymer and atactic polypropylene byselection of the unsaturated diene monomer used in the anionicpolymerization process.

In a further exemplary embodiment of the present disclosure, thedisclosed hyperbranched or dendritic saturated hydrocarbon polymers maybe formed in a single step reaction comprising unsaturated dienemonomers and coupling agents.

These and other advantages, features and attributes of the disclosedhyperbranched or dendritic saturated hydrocarbon polymers and method ofsynthesizing of the present disclosure and their advantageousapplications and/or uses will be apparent from the detailed descriptionwhich follows, particularly when read in conjunction with the figuresappended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

To assist those of ordinary skill in the relevant art in making andusing the subject matter hereof, reference is made to the appendeddrawings, wherein:

FIG. 1 depicts an illustrative schematic of the prior art back bitingreaction for free radical chain branching.

FIG. 2 depicts an illustrative schematic of the prior art chaintermination reaction for free radical branching.

FIG. 3 depicts an illustrative schematic of a double-tailed macromonomervia anionic synthesis.

FIG. 4 depicts an illustrative schematic of a double macromonomerproduced by linking two living butadiene chains via a diphenylethylenesilane coupling agent.

FIG. 5 depicts an illustrative schematic of a 1^(st) generationbutadiene-lithium branch structure.

FIG. 6 depicts an illustrative schematic of a well-defined, 1^(st)generation dendritic polybutadiene structure.

FIG. 7 depicts an illustrative schematic of a 2^(nd) generationbutadiene-lithium branch structure.

FIG. 8 depicts an illustrative schematic of a well-defined, 2ndgeneration dendritic polybutadiene structure.

FIG. 9 depicts an illustrative schematic of a double macromonomerproduced by linking two living butadiene chains via a styryl silanecoupling agent.

FIG. 10 depicts an illustrative schematic of a double comb branchstructure.

FIG. 11 depicts a graphical representation of the Theological behavior(η*versus ω) of 3% of PEDC1 in 97% of EX350D60 and 100% EX350D60.

FIG. 12 depicts a graphical representation of the rheological behavior(δ versus G*) of 3% of PEDC1 in 97% of EX350D60 and 100% EX350D60.

FIG. 13 depicts an illustrative schematic of synthesized novelmacromolecular structures based on double-tipped polybutadiene (PBd)macromonomers.

FIG. 14 depicts the general reaction scheme for the synthesis ofstyrenic-tipped double-macromonomers of PBd and PBd double-combs.

FIG. 15 depicts an illustrative schematic of the apparatus for thesynthesis of the Grignard reagent and 4-(dichloromethylsilyl)styrene. C:1,2-dibromoethane in THF, B: p-chlorobenzene; F: trichloromethylsilane.

FIG. 16 depicts the general reaction scheme for the synthesis of4-(dichloromethylsilyl) styrene (DCMSS).

FIG. 17 depicts the ¹H-NMR spectrum of 4-(dichloromethylsilyl)styrene.

FIG. 18 depicts an illustrative schematic of the apparatus for thesynthesis of linear/star double combs and double-molecular brushes.

FIG. 19 depicts size exclusion chromatograms of PBd branch (A),styrenic-tipped double-macromonomers (B) and the correspondingdouble-comb.

FIG. 20 depicts size exclusion chromatograms of PBd branch (A),styrenic-tipped double-macromonomer (B), double-comb (C), unfractionatedstar (D), fractionated star (E).

FIG. 21 depicts size exclusion chromatograms of PBd branch (A), PBdmacromonomer (B), and the corresponding double-polymacromonomer(C)(Sample 1-Table 3).

FIG. 22 depicts the reaction scheme for the synthesis of4-(dichloromethylsilyl)diphenylethylene (DCMSDPE).

FIG. 23 depicts the reaction scheme for the synthesis ofthird-generation dendritic polymers.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to improved compositions, method ofsynthesizing, and uses of highly-branched saturated hydrocarbonpolymers. The highly-branched saturated hydrocarbon polymers and processof synthesizing of the present invention are distinguishable over theprior art in permitting a more precise placement of the chain branchesand a narrower distribution of both chain branch length and number ofchain branches. More particularly, new and well-defined polyethylenescan be used to better understand the way that the behavior of HP-LDPE iscontrolled by the architecture of the molecules from which it is made.

Synthesis of Model LDPE: The challenge in making these molecules is toproduce the branching at many levels with a well-controlled procedure,rather than the random processes that characterize free radicalchemistry processes. The reaction scheme depicted below shows how toprepare well-defined PE with one branched branch. The monomer-scalestructure of these chains will resemble ethylene-butene copolymers.Butadiene units can go into the chain at either the 1,4 or 1,2 positionswith the former position being identical to two ethylene repeat unitsafter saturation, while the latter position is the same as one buteneunit. Generally the polybutadiene will have around 8% 1,2, so thesaturated analogue will resemble an EB with 8 wt % butene. This amountof short chain branches is very similar to that of HP-LDPE. Thesynthetic methodology is as follows.

Anionic synthesis of double-tailed macromonomer. Due to the livingnature of this chemistry, the produced polymer will be nearlymonodisperse, and the terminal carbon anion as depicted in FIG. 3 allowsfor further linking chemistry.Bd+sec-BuLi→(PBd₁)⁻Li⁺ (Bd=Butadiene)

Linking polybutadiene to diphenylethylene silane coupling agent: Byattaching this group to two living chains, a double macromonomer asdepicted in FIG. 4 can be prepared. This may be done using dichloromethyl silyl diphenylethylene [DCMSDPE, Cl₂Si(CH₃)C₆H₄(C₆H₈)CH═CH₂]asfollows to yield the following structure.(PBd₁)⁻Li⁺+(PBd₂)⁻Li⁺+DCMCDPE→(PBd₁)(PBd₂)Si(CH₃)C₆H₄(C₆H₅)CH═CH₂+2LiCl

Polymerizing the third chain: By adding s-BuLi and more butadienemonomer, a third, nearly monodisperse chain polymerizes from the middleactive center as depicted in FIG. 5 via the following reaction. Sinceeach of these three chains can be polymerized independently, they caneach have whatever length is required.(PBd₁)(PBd₂)Si(CH₃)C₆H₄(C₆H₅)CH═CH₂+s-BuLi+Bd→(PBd₁)(PBd₂)Si(CH₃)C₆H₄(C₆H₅)(PBd₃)⁻Li⁺

-   -   (1st Generation living Branch, 1G-B—Li, branch on branch)

Combining 1G-B—Li to make well-defined, dendritic PBd: A highly branchedPBd as depicted in FIG. 6 is then made by coupling three of thesemolecules with trichloro silane via the following reaction.3(PBd₁)(PBd₂)Si(CH₃)C₆H₄(C₆H₈)(PBd₃)⁻Li⁺+(CH₃)SiCl₃→wd-PBd+3LiCl

Hydrogenation of the wd-PBd gives wd-PE. We have thus made a highlybranched PE polymer where the molecular weights of each section are veryprecisely controlled and can be varied independently. One importantfactor is to be sure that each branch section is several times theentanglement molecular weight, which is ˜1.1 kg/mol for PE.

The degree of branching can be increased even further. If instead ofreacting with (CH₃)SiCl₃ the 1G-B—Li is reacted with more DCMSDPE,followed by addition of other living polymers, plus subsequentpolymerization of the monomer by the new formed active species, we mayproduce 2G-B—Li as depicted in FIG. 7.

By reaction of the produced 2G-B—Li with (CH₃)SiCl₃ and hydrogenation, asecond generation wd-PE that has branch-on-branch-on-branch structure isproduced as depicted in FIG. 8.

Even greater degrees of complexity can be achieved by usinghydrosilylation chemistry on PBd as disclosed in U.S. Pat. Nos.6,355,757, 6,391,998, and 6,417,281 herein incorporated by reference,and reacting the Si—Cl side groups with the 2G-B—Li. Once this ishydrogenated, a wd-PE with many branches-on-branches-on-branches will beproduced. A wide range of well-defined, highly branched structures arethus made possible by this chemistry.

Linking Polybutadiene to Styryl Silane Linking Agent:

The double-tailed macromonomer as depicted in FIG. 9 can also beprepared by linking living chains to styryl silane [SS,Cl₂Si(CH₃)C₆H₄CH═CH₂] as shown by the following reaction:(PBd₁)⁻Li⁺+(PBd₂)⁻Li⁺+SS→(PBd₁)(PBd₂)Si(CH₃)C₆H₄CH═CH₂+2LiCl

Copolymerizing this with more butadiene in the presence of a randomizersuch as potassium 2,3-dimethyl-pentoxide-3 [R—O⁻K⁺] leads to theso-called ‘double-comb’ structure as depicted in FIG. 10 and in thefollowing reaction scheme:(PBd₁)(PBd₂)Si(CH₃)C₆H₄CH═CH₂+s-BuLi+Bd+R—O⁻K⁺→DC Li⁺

In turn these double combs can be linked just as the linear chains wereabove to make highly branched dendritic structures. This chemistry isnot limited to making model PE long chain branching structures. Ifisoprene is used in place of butadiene, the same procedures lead towd-ethylene-propylene copolymer, since hydrogenated polyisoprene has thestructure of an alternating ethylene-propylene copolymer. Atacticpolypropylene branched polymers can also be made using2-methyl-1,3-pentadiene as the monomer. Many other polyolefinic branchedpolymers can be made by this general synthesis technique. Besidesbutadiene, isoprene, and 2-methyl-1,3 pentadiene, other dienes that willpolymerize using anionic initiators include, but are not limited to,2-ethyl-1,3-pentadiene, 2-propyl-1,3-pentadiene, 2-butyl-1,3-pentadiene,2-pentyl-1,3-pentadiene, 2-hexyl-1,3-pentadiene, 2-ethyl-1,3-butadiene,2-propyl-1,3-butadiene, 2-butyl-1,3-butadiene, 2-pentyl-1,3-butadiene,2-hexyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene,2,3-diethyl-1,3-butadiene, 2,3-dipropyl-1,3-butadiene,2,3-dibutyl-1,3-butadiene, 2,3-dipentyl-1,3-butadiene,2,3-dihexyl-1,3-butadiene, myrcene (7-methyl-3-methylene-1,6-octadiene),1,3 cyclohexadiene, other 2-alkyl-1,3-pentadienes, other2-alkyl-1,3-butadienes, and other 2,3-dialkyl-1,3-butadienes.

The double-comb and dendritic saturated hydrocarbon polymer compositionsof the instant invention may find application in for example, but notlimited to, blending with LLDPE, HDPE, HMW HDPE and other linearpolyolefins, to improve processability without a loss of mechanicalproperties. For example, the use of such double-comb and dendriticsaturated hydrocarbon polymer compositions as additives will delay theonset of melt fracture, enabling higher rates of extrusion in theproduction of films, pipes, fibers and other extruded forms. The use ofsuch double-comb and dendritic saturated hydrocarbon polymercompositions as additives will also find utility in injection moldingprocesses for improving flow properties of LLDPE, HDPE, HMW HDPE, andother linear polyolefins, such as to improve melt output rates bydelaying the onset of melt fracture and improving processability. Only asmall or minor amount of a particular kind of long chain branching issufficient to yield many of the beneficial flow effects of HP-LDPE inextrusion and injection molding processes. The double-comb and dendriticsaturated hydrocarbon polymer compositions of the instant invention maybe blended with other polyolefins via a number of blending techniquesknown to those skilled in the art, for example, but not limited to,solution blending and melt blending with other polymers. The otherpolyolefins will constitute the major amount of the blend.

Applicants have attempted to disclose all embodiments and applicationsof the disclosed subject matter that could be reasonably foreseen.However, there may be unforeseeable, insubstantial modifications thatremain as equivalents. While the present invention has been described inconjunction with specific, exemplary embodiments thereof, it is evidentthat many alterations, modifications, and variations will be apparent tothose skilled in the art in light of the foregoing description withoutdeparting from the spirit or scope of the present disclosure.Accordingly, the present disclosure is intended to embrace all suchalterations, modifications, and variations of the above detaileddescription.

The following examples from feasibility studies to produce model doublecomb structures (FIG. 13) and dendritic structures based ondouble-tipped polybutadiene macromonomers illustrate the presentinvention and the advantages thereto without limiting the scope thereof.

EXAMPLES

Double Comb Polymer Examples

Reagents: The purification of the monomer (butadiene, 99% Aldrich), thesolvents (benzene, 99.8% Aldrich, and THF, 99.9% Aldrich), theterminating (methanol, 99.9% Aldrich) and the linking agent [Cl₃(CH₃)Si,99% Aldrich], to the standards required for anionic polymerization, wasperformed using well-established high-vacuum procedures.sec-butyllithium (sec-BuLi), prepared from sec-butylchloride (99.9%Aldrich) and lithium dispersion (99%, high sodium, Aldrich), was theinitiator for all polymerizations. Magnesium turnings (Aldrich) werewashed with HCl 0.1N, diethyl ether (99.9%, Aldrich) and acetone (99.9%,Aldrich), and then left to dry in vacuum oven overnight. p-chlorostyrene(97%, Aldrich) was distilled in the vacuum-line, from calcium hydride,to ampoules equipped with break-seals. Potassium2,3-dimethyl-pentoxide-3 (R—O⁻K⁺), the randomizer, was prepared from2,3-dimethyl-3-pentanol (99%, Aldrich) and potassium in a proceduresimilar to the one used for the synthesis of sec-BuLi. n-BuLi in hexane(1.6 N, Aldrich) was used as received.

Synthesis of 4-(dichloromethylsilyl)styrene:4-(dichloromethylsilyl)styrene (DCMSS) was prepared from the Grignardreaction of p-chlorostyrene and trichloromethylsilane according to thereaction scheme in FIG. 14. A specially designed apparatus, consistingof two flasks (F1 and F2), and equipped with a condenser and ampouleswith the reagents were used for the synthesis of4-(dichloromethylsilyl)styrene (DCMSS) (FIG. 15). Before use, the F1section was rinsed with Cl(CH₃)₃Si for elimination of internal glassimpurities. The F2 section was also rinsed with Cl(CH₃)₃Si before beingattached to the F1 flask and was dried on the vacuum line through aground joint that existed in G. After introducing magnesium turnings tothe flask F1, through the tube, the tube was closed with a septum, theapparatus was attached to the vacuum line through a ground joint,evacuated and the tube with the septum was sealed off. A solutioncontaining a few drops of 1,2-dibromoethane in 30 ml of THF was added toF1, from the ampoule C, after breaking the corresponding break-seal, andthe mixture was stirred for a few minutes to activate the magnesium. Theproduced ethane was eliminated through the vacuum line, and theapparatus was sealed off at A. An appropriate amount of p-chlorostyrene(mol p-chlorostyrene/mol Mg=1/1.5), purified by distillation overcalcium hydride, was introduced drop-wise to the flask after breakingthe break-seal of ampoule B, while maintaining the reflux of THF. Duringthe last 30 minutes of the addition of p-chlorostyrene the reflux wassupported through slightly heating (˜30° C.), which was maintained evenafter the addition of the whole amount (˜2h) for another 1 h. Thetrichloromethylsilane solution (mol MeSiCl₃/mol p-chlorostyrene=2/1) wasthen introduced to the flask F2 from ampoule J. After cooling F2 at 0°C., the break seal E, which connects the two flasks, was broken and theGrignard reagent, prepared in F1, was added carefully and drop-wise tothe silane solution (flask F2), during ˜90 min. The section of F1 waseliminated by sealing-off at D. The solution in F2 was left to react forone more hour. The produced DCMSS was transferred, under vacuum, into aspecially designed apparatus and distilled twice. The first distillationwas to separate DCMSS from MgCl₂, produced during the Grignard reaction,and the second one to purify DCMSS. The yield of the whole procedure wasabout 80%. A typical synthesized quantity of DCMSS was about 8 g.Finally the purified DCMSS was diluted with benzene, and stored at −20°C. in ampoules equipped with break-seals. The ¹H NMR spectrum for DCMSS(300 MHz, CDCl₃), depicted in FIG. 17, confirmed the successfulsynthesis of DCMSS. As the peak of the OH protons cannot be seen, we canassume that a dimmer or a tetramer of DCMSS with Si—O—Si bonds wassynthesized when the sample of DCMSS interacts with air: δ 6 7.42-7.59(C₆H₄), doublet 5.33-5.9 (CH₂═CH), triplet 6.75-6.82 (CH₂═CH), singlet1.15 (CH₃—Si—). Integration of the peaks gave the expected ratios forDCMSS.

Synthesis of double-comb polybutadienes: Polymerizations were carriedout in evacuated, n-BuLi-washed, and solvent-rinsed glass reactors.Reagents were introduced via break-seals and aliquots forcharacterization were removed by heat-sealing of constrictions. Fulldetails of the high vacuum techniques are given elsewhere. The apparatus(FIG. 18) was attached to the vacuum line and was evacuated. A fewmilliliters of n-BuLi solution in n-hexane were introduced through theseptum. After distilling benzene through the vacuum line, the apparatuswas again evacuated and sealed off at constriction A. It was purged withthe n-BuLi benzene solution, and the purging section was removed byheat-sealing at constriction C. The 4-(dichloromethylsilyl) styrene wasintroduced to the main reactor by breaking the corresponding break-seal.The break-seal of the corresponding ampoule-flask was then broken andthe PBdLi, prepared in a secondary reactor and connected to theapparatus, was added drop-wise to the solution of DCMSS. The reactionwas monitored by removing small aliquots and analyzing them with SEC.After ˜2 equivalents of PBdLi, relative to DCMSS, had been added to thereactor, and more importantly when the end point was judged by SEC, thetitration was stopped. The procedure of the titration lasted about threehours. The linking reaction of the first branch with DCMSS took place inabout two hours and the reaction of the second branch in the last houras the reaction was quite decelerated. The flask containing the excessof the living polybutadiene solution was then removed by heat sealing(constriction B). Butadiene was then added to the main reactor and afterthat the initiator sec-BuLi and the randomizer R—O⁻K⁺ were also added atthe same time into the main reactor. The polymerization was monitored byremoving small samples and analyzing them by SEC. The reaction wasconsidered complete only when the SEC peak of the macromonomer wasdisappeared. After the completion of the copolymerization (3-4 days),the double-comb PBd was terminated with degassed methanol, precipitatedinto an excess of methanol, and dried under vacuum, until constantweight.

Synthesis of star double-comb polybutadienes: The same procedure andapparatus was used here as for the linear double-comb polymers. Theapparatus has one more ampoule with the linking agenttrichloromethylsilane (—SiCl/C—Li=1/1.3). After the completion of thelinking reaction (˜ two weeks) the excess linear double-comb precursorwas eliminated by the well-known solvent (toluene)—non-solvent(methanol) fractionation methodology.

Synthesis of double-polymacromonomers: The preparation of the moleculardouble-brushes (double-polymacromonomers) followed a similar procedure.The reactor has an ampoule of sec-BuLi instead of butadiene and norandomizer (R—OK) was used. A deep, bright yellow color appearedimmediately after the addition of the initiator. The homopolymerizationof the macromonomer was completed in 4-5 days.

Molecular Characterization: SEC analysis was performed using a WatersHPLC system equipped with a Waters 501 high pressure liquidchromatographic pump, four Waters Styragel columns having a porosityrange of 10²-10⁶ Å, a Waters 410 differential refractometer detector anda UV detector. Tetrahydrofuran was the eluent at a rate of 1 mL/min at30° C. The instrument was used to determine the polydispersity factor(I=M_(w)/M_(n)) of all samples and the M_(n) of the PBddouble-macromonomers. Calibration was performed with seven standard PBdsamples covering the molecular weight range from 2 to 350 kg/mol.Multi-detector GPC analysis (GPC-RI and GPC-TALLS) was performed using aWaters system equipped with a Waters 1525 high pressure liquidchromatographic pump, Waters Ultrastyragel columns (HR-2, HR-4, HR-5Eand HR-6E) with THF eluent at a rate of 1 mL/min at 30° C. A Waters 2410differential refractometer detector and a Precision PD 2020 two angles(15°, 90°) light scattering detector at 35° C. were used. The instrumentwas used to determine the M_(w) and mean square radius of gyration<S²>of the double-comb precursors/final products. The NMR spectra of theDCMSS and PBd macromonomers were obtained by a Varian Unity Plus 300/54instrument in CDCl₃ at room temperature. The analysis showed that thefinal comb has practically the same microstructure (1,4˜93%; 1,2˜7%) aswithout the presence of the potassium alkoxide.

The general synthetic route followed for the synthesis of double-tailedmacromonomers and their anionic copolymerization with butadiene is givenin FIG. 16. The key factor for the synthesis of the double-macromonomersis the faster reaction of the living polymer with the chlorines of thechlorosilane group (S_(N)) than with the double bond (addition) ofDCMSS. The orange color of the styrenic-tipped anion produced, from thereaction of the slight excess living chain with the double bond ofDCMSS, allows the visual monitoring of the end-point of the linkingreaction. In the case when the molecular weight of the living polymerwas higher than 10 kg/mol the stereochemical hindrance almost completelyinhibited the reaction with the double bond and visual monitoring of theend point of the linking reaction becomes impossible. The process of thecoupling in this case was monitored by SEC.

The key factor for the synthesis of double-comb polybutadienes, dcPBd,was the copolymerization of the macromonomer with butadiene in the samereactor used for the preparation of macromonomer without isolation.Isolation of the macromonomer (precipitation in a non-solvent)introduces impurities. Since the macromonomers are solid materials,their purification to the standards required for anionic polymerizationis extremely difficult or impossible, which is the reason that previousattempts failed. The difference between the reactivity ratios of thestyrenic-tipped macromonomer and the butadiene monomer led to undesiredtapered copolymers. In order to decrease the difference in reactivityratios and to prepare random combs, the addition of a polar reagent isrequired. This additive was used in a ratio mole_(s-BuLi)/mole_(R—O) ⁻_(K) ⁺ equal to 30/1. During the copolymerization the solution had thecharacteristic color of PBdLi meaning that the copolymerization wasrandom. The copolymerization was monitored by SEC. A typical example isgiven in FIG. 19. The average number of branch points, p, can becalculated by using the relationship (1) below, given the fact that thetwo monomers, the macromonomer (sMM) and butadiene (Bd) are transformedpractically completely to copolymers:

$\begin{matrix}\begin{matrix}{p = \frac{{mol}_{sMM}}{{mol}_{{double} - {comb}}}} \\{= \frac{W_{sMM}/M_{n,{sMM}}}{\left( {W_{backbone} + W_{sMM}} \right)/M_{n,{{double} - {comb}}}}} \\{= \frac{W_{sMM} \cdot M_{n,{{double} - {comb}}}}{\left( {W_{Bd} + W_{sMM}} \right) \cdot M_{n,{sMM}}}}\end{matrix} & (1)\end{matrix}$

where W_(sMM) and W_(backbone) (=W_(Bd)) are the weight of the twomonomers (sMM, Bd) and M_(n,sMM) M_(n,double-comb) the M_(n) of thedouble macromonomer and double-comb, respectively. The molecularcharacteristics are summarized in Table 1 below:

TABLE 1 Molecular characteristics of PBd branches, styrenic-tippeddouble-tailed macromonomers and corresponding double-combs Double-TailedMacro- PBd branch monomer Double Comb M_(w) ^(a) M_(w) ^(a) M_(w) ^(a)(kg/ (kg/ (kg/ Sample p^(c) mol) M_(w)/M_(n) ^(b) mol) M_(w)/M_(n) ^(b)mol) M_(w)/M_(n) ^(b) dcPBd1 3.1 5.08 1.03 10.2 1.08 136 1.07 dcPBd2 3.09.41 1.02 18.9 1.01 143 1.06 dcPBd3 3.2 13.3 1.02 26.6 1.01 177 1.10dcPBd4 2.5 26.3 1.02 52.6 1.06 256 1.10 dcPBd5 4.0 4.30 1.04 8.6 1.04108 1.07 ^(a)SEC-TALLS in THF at 35° C., ^(b)Size ExclusionChromatography (SEC) in THF at 30° C., using PBd standards. ^(c)Averagenumber of branch points per chain.

Another way to prove that the double combs exhibited the structureclaimed is to compare the experimental values (light scattering) of theZimm-Stockmayer parameter g=

S²

_(branched)/

S²

_(linear) with the theoretical ones.

S²

 is the mean square radius of gyration of the branched and linearmacromolecules with the same total molecular weight. The theoreticalvalues, g_(theor), were calculated by using the following relationship(2) of Orofino-Berry, valid for most of branched structures examineduntil now, after appropriate modifications.

$\begin{matrix}{g_{theor} = \left\{ \frac{{\left( {f - 2} \right){p\left\lbrack {{3{p\left( {f - 2} \right)}} - 2} \right\rbrack}r^{3}} + {\left( {f - 2} \right){{p\left( {p + 1} \right)}\left\lbrack {{\left( {f - 2} \right)\left( {p - 1} \right)} + 3} \right\rbrack}r^{2}} + {\left( {f - 2} \right){p\left( {p + 1} \right)}\left( {{2p} + 1} \right)r} + \left( {p + 1} \right)^{3}}{\left\lbrack {{\left( {f - 2} \right){rp}} + p + 1} \right\rbrack^{3}} \right\}} & (2)\end{matrix}$

where ƒ is the functionality of the branch points (=4),r=M_(w branch)/M_(w connector), and M_(w connector) is the averagemolecular weight between two branch points. The g_(exp) and g_(theor)are given in Table 2 below. The

S²

_(linear) values were calculated from the following experimentallyestablished equation (3) valid for PBd in a good solvent.

S ²

^(1/2)=1.29×10⁻² M ^(0.609)  (3)

TABLE 2 Values of the shrinkage factor g for the double-combs.<S²>^(1/2) (nm) G Sample double-comb Linear experimental theoreticaldcPBd1 15.1 17.25 0.77 0.75 dcPBd2 14.2 17.76 0.64 0.63 dcPBd3 14.920.27 0.54 0.56 dcPBd4 19.3 25.33 0.58 0.55 dcPBd5 12.0 15.00 0.64 0.67

A symmetric star having three branches of double-comb PBd was preparedby reacting an excess of the living double-comb PBd with Cl₃(CH₃)Si,instead of terminating it with methanol. The star was fractionated untilall desirable product was isolated from the reacting double-comb with asolvent/non solvent mixture of toluene/MeOH. The chromatograms of theliving branch, the macromonomer, the double-comb, the unfractionated andthe fractionated star-double-comb are given in FIG. 20 and the molecularcharacteristics are summarized in Table 3.

TABLE 3 Molecular characteristics of PBd branch, styrenic-tipped double-macromonomer, double-comb and corresponding symmetric star PBd branchMacromonomer Double Comb Star M_(n) ^(b) M_(w) ^(a) M_(w) ^(b) M_(w)^(a) Sample (kg/mol) M_(w)/M_(n) ^(a) (kg/mol) M_(w)/M_(n) ^(a) (kg/mol)M_(w)/M_(n) ^(a) (kg/mol) M_(w)/M_(n) ^(a) 1 4.30 1.04 8.6 1.04 108 1.07340 1.07 ^(a)Size exclusion Chromatography (SEC) in THF at 30° C., usingPBd standards, ^(b)SEC-TALLS in THF at 35° C.

Finally a typical example of the synthesis of double-molecular brushes,as monitored by SEC is given in FIG. 19 and the molecularcharacteristics are summarized in Table 4.

TABLE 4 Molecular characteristics of PBd branches, styrenic-tippedmacromonomers and corresponding polymacromonomers. Macro- Poly- PBdbranch monomer macromonomer M_(n) ^(b) M_(w) ^(a) M_(w) ^(b) (kg/ (kg/(kg/ Sample mol) M_(w)/M_(n) ^(a) mol) M_(w)/M_(n) ^(a) mol) M_(w)/M_(n)^(a) X_(n) ^(c) 1 4.30 1.04 8.6 1.04 69.0 1.09 8.0 2 8.80 1.02 17.6 1.03158 1.09 9.0 3 1.34 1.09 2.7 1.09 79.5 1.05 29.4 4 3.19 1.04 6.4 1.0564.0 1.10 10.0 ^(a)Size exclusion Chromatography (SEC) in THF at 30° C.,using PBd standards, ^(b)SEC-TALLS in THF at 35° C., ^(c)Degree ofpolymerization.Double Comb Hydrogenation Examples

Hydrogenation: The polybutadienes were saturated catalytically.Typically the polybutadiene was dissolved in cyclohexane and reactedwith H₂ gas at 90° C. and 700 psi in the presence of a catalyst made bysupporting Pd on CaCO₃. The mass of catalyst used was equal to that ofthe polymer. The reaction was allowed to proceed until the H₂ pressurestopped dropping, or generally about 24 h. The polymer solution was thenfiltered to remove the catalyst residues. The saturation of the polymerwas seen to be greater than 99.5% by ¹H NMR. The result in each case wasa model for polyethylene.

Double Comb Polymer Rheology:

In particular, one of these (which we call PEDC1) has a backbone ofmolecular weight 100 kg/mol and three branch points, each having twoarms of molecular weight 5 kg/mol. We have measured the rheology of ablend with 3% of PEDC1 in 97% of EX350D60, as well as that of the pureEX350D60. The effects are dramatic, as can be seen in FIGS. 11 and 12.FIG. 11 shows how the shear thinning of the PE is greatly enhanced bythe addition of small amounts of the branched model polymer, while FIG.12 depicts the same behavior in the form of the Van Gurp plot. Thesepolymers will be extremely effective processability modifiers forpolyolefins. The linear viscoelastic properties (dynamic moduli) ofthese polymers were measured with a Paar-Physica (MCR-500) controlledstress rheometer. Measurements were performed at 190° C. using aparallel plate (d=25 mm) geometry. Linearity of the mechanical responsewas obtained with a variable stress input (2000 Pa to 100 Pa) over afrequency range of 100 rad/s to 1 rad/s. Nitrogen atmosphere was usedduring the test to minimize thermally induced chemical changes. Theso-called Van-Gurp plot (phase angle δ=tan⁻¹(G″/G′) plotted against thelog of the absolute value of the complex modulus, |G*|) provides anexcellent means to analyze linear viscoelasticity. This representationrenders a plot invariant of the temperature and the molecular weight,but very sensitive to the effects of the molecular weight distributionand the presence of short and long chain branching. FIG. 13 nicely showsthat the addition of long chain branching component makes the modelblend more elastic than the linear polymer (EX350D60), and introduces apower law relaxation region (between 10 and 50 kPa)

Dendritic Polymer Examples

Materials: Butadiene (Aldrich; >99%), all solvents [tetrahydrofuran,benzene, and hexane, all reagent-grade], the terminating agent(methanol), and the coupling agent (trichloromethylsilane,Aldrich; >99%) were purified using high-vacuum techniques and standardprocedures described in detail elsewhere. sec-Butylchloride (99.9%,Aldrich), dried over CaH₂ overnight, degassed, and distilled in a vacuumline, was reacted, in a suitable high-vacuum apparatus, with excess Li(99% with high sodium, Aldrich) in hexane to produce the initiator,s-BuLi. Methyltriphenylphosphonium iodide (97%, Aldrich), n-BuLi (1.6 Min hexane, Aldrich), 4-Bromobenzophenone (98%, Aldrich), and MgSO₄ wereused as received. Magnesium turnings (Aldrich) were activated bysequential washings with a 0.1 N HCl solution (two times), distilledwater (five times), diethyl ether (five times), and acetone (five times)and dried in a vacuum oven to a constant weight. Similar apparati andthe same characterization methods were used as in the case of thedouble-tailed combs.

Synthesis of 4-(Dichloromethylsilyl)diphenylenthylene (DCMSDPE): DCMSDPEwas prepared from the Grignard reagent of 4-bromodiphenylethylene andtrichlorodimethylsilane using specially designed apparati andhigh-vacuum techniques. 4-bromodiphenylethylene the product of theWittig reaction between 4-bromobenzophenone andmethyltriphenylphosphonium iodide, in the presence of n-BuLi. Thesynthetic route is given in FIG. 22 and the experimental procedure is asfollows. To a 500 mL round-bottom flask fitted with a dry nitrogen inletseptum, methyltriphenylphosphonium iodide (31 g, 76 mmol) was suspendedin dry THF under a nitrogen atmosphere. n-BuLi (47.5 mL of 1.6 M inhexane, 76 mmol) was added to the suspension at room temperature withstirring. The mixture became dark red, and the solution was allowed tostir for an additional half-hour. 4-Bromobenzophenone (20 g, 76 mmol)was then added via a syringe over 30 min with vigorous stirring at roomtemperature. The mixture became yellow and was stirred overnight at roomtemperature under a nitrogen atmosphere and then diluted with 150 mL ofchloroform and 150 mL of dilute hydrochloric acid aqueous solution (0.1N). The organic phase was collected, washed, and dried over MgSO₄. Thesolvent was removed by rotor evaporation and ˜100 mL of hexane wereadded. The precipitate was filtered and the hexane solvent condensed,followed by a new addition of hexane. This procedure was repeatedseveral times until no precipitation took place after addition ofhexane. The resultant residue was purified by chromatography on silicagel using n-hexane as the eluent to yield ˜10 g of 4-bromo-DPE as ayellow oil.

Synthesis of DCMSDPE: A special designed glass apparatus (FIG. 15) wasused for the synthesis of DCMSDPE. After introducing magnesium turnings(1.9 g, 78.2 mmol) through the tube B, the tube was closed with aseptum, the apparatus was attached to the vacuum line through a groundjoint, evacuated, and sealed off at the tube B. A solution of a fewdrops of 1,2-dibromoethane in 20 mL of THF (ampoule C) was added to theflask and the mixture was stirred for a few minutes to activate themagnesium. The produced ethane was eliminated, and the apparatus wassealed off at a. A small portion of 4-bromo-DPE (5 g, 19.3 mmol) in 30mL of THF (ampoule D) was introduced dropwise to the flask whilemaintaining the reflux of THF. After the addition was completed (˜1 h),the reaction mixture was allowed to stir for an additional 5 h at 45° C.The trichloromethylsilane diluted in 20 mL of THF (5.8 g, 38.8 mmol)(ampoule E) was first introduced to the main flask F2, and after coolingat 0° C. the Grignard reagent was added drop-wise to the silane solutionin ˜90 min. The reaction mixture was allowed to stir for an additional 1h at 0° C. Flask F2, as well as all the apparatuses that were used fromthis point up to final distillation of the pure DCMSDPE had been firstrinsed with Me₃SiCl and dried on the vacuum line overnight.

The crude product of the reaction (containing DCMSDPE, THF and excessMeSiCl₃) was condensed in the vacuum line to eliminate the volatilecompounds and ˜120 ml of hexane were distilled into the flask F2 (FIG.15). After evacuating and detaching the flask from the vacuum line, thesolution was kept at −20° C. for 2 days until partial precipitation ofMgBrCl and then was filtered through a glass filter to the second flaskF3 of the apparatus. The product was left in the vacuum line (10⁻⁶Torr), with continuous stirring at 40° C., for 3 h to eliminate the lasttraces of hexane, THF and MeSiCl₃ and was subsequently distilled, at ahigh temperature (140-150° C.), into a new apparatus (FIG. 15) toseparate DCMSDPE from MgBrCl and other solid byproducts, e.g., thermallypolymerized DCMSDPE). Finally, pure DCMSDPE (3 g, 10.2 mmol) wasdistilled into ampoules at ˜110° C., diluted in benzene, and stored at−20° C. The ¹H NM spectrum confirms the successful synthesis of DCMSDPE.¹H NMR (CDCl₃): δ 7.7-7.8 (2H, d, Ar—H), 7.46-7.52 (2H, d, Ar—H), 7.37(5H, m, Ar—H), 5.55-5.62 (2H, d, C═CH₂), 2.34 (1H, m, Si—OH), 1.1 (3H,m, Si—CH₃). Integration gave the expected ratios of the protons.

Dendritic Polymer Synthesis:

Polymerization and linking reactions were carried out in evacuated,n-BuLi washed and solvent-rinsed glass reactors. Reagents were added viabreak-seals, and aliquots for characterization were removed byheat-sealing of constrictions. Full details of the apparatuses andtechniques used are given elsewhere. The synthetic route is given inFIG. 23.

Synthesis of G-2 Dendritic Polymers:

The living polybutadiene (PBLi) was synthesized by polymerization of thebutadiene monomer with s-BuLi in benzene at room temperature for 24 h,collected in a precalibrated ampoule equipped with break-seal andconnected to the macromonomer synthesis apparatus (FIG. 15). The livingpolybutadiene (8 g in 50 mL of benzene, M_(W(TALLS))=4.79 Kg/mol , 1.7mmol) of the G-2 branch was added dropwise to the reactor F5 containingDCMSDPE in benzene (0.176 g, 0.6 mmol in 100 mL of benzene) withcontinuous and vigorous stirring. The reaction was monitored by takingsamples (F) and analyzing them by SEC. After ˜2 equiv of PBdLi (5.7 g,1.2 mmol), relatively to DCMSDPE, had been added to the reactor, andwhen the end point was judged by SEC, the titration was stopped. Theaddition was carried out over a period of approximately 12 h, after thefirst six hours a permanent yellow color appeared. The excess living PBd(2.3 g, 0.5 mmol) was removed from the apparatus by heat-sealing theconstriction of the corresponding ampoule. The solution of themacromonomer was then transferred into flask F6 and was connected to asecond apparatus (FIG. 18) where firstly the appropriate amount ofinitiator s-BuLi (0.6 mmol) was added. The color immediately turned fromyellow to deep red indicating the opening of the double bond of thediphenylethylene, which consists the end group of the macromonomer. Thesolution was left under stirring for 48 hours, in order to ensure thatall the DPE groups react with s-BuLi. The appropriate quantity ofbutadiene (2.5 g) was added and after complete polymerization (˜24 h) analiquot was taken from the reactor for characterization and the linkingagent, trichlomethylsilane (0.16 mmol), was introduced. The reaction wasmonitored by removing small aliquots and analyzing them by SEC. Thelinking reaction was completed in 25 days. The reaction product, afterneutralization of the excess of the living species with degassedmethanol, was fractionated by the toluene/methanol system. Thefractionated G-2 dendritic copolymer was precipitated into an excess ofmethanol and dried under vacuum, until constant weight. The molecularcharacterization results are given in Table 5.

TABLE 5 M_(w) ^(b) Arm M_(w) ^(b) Arm (G-2) (G-1) M_(w) ^(c) DendriteM_(w) ^(b) Dendrite (M_(w)/M_(n))^(a) Weight Sample (kg/mol) (kg/mol)(kg/mol) (kg/mol) dendrite (g) 1 3.25 5.55 36.15 34.74 1.04 0.8 2 4.7913.97 70.65 65.25 1.07 0.6 3 14.30 12.16 122.28 115.37 1.05 1.36 4 18.9823.24 183.60 172.93 1.05 3.66 5 25.06 21.43 214.65 6 M_(n) ^(a) = 38.01^(a)SEC in THF at 30° C., using PBd standards. ^(b)Obtained by SEC-TALLSin THF at ^(c)Calculated from the molecular weights of the arms.Synthesis of G-3 Dendritic Polymers:

The preparation firstly of the linear living polybutadiene branch (8 g,M_(w(TALLS))=4.79 kg/mol , 1.7 mmol) and secondly of the livingthree-arm star PBd⁻Li⁺ (8.2, 0.6 mmoles) followed exactly the sameprocedure as mentioned for the synthesis of G-2 dendritic polymers. Inthis case the produced living polybutadiene star (PBd⁻Li⁺) was collectedinto flask F7 and connected to a new apparatus similar to the one ofFIG. 15, where a second titration took place. PBd⁻Li⁺ was added dropwiseto the reactor containing DCMSDPE in benzene (0.07 g, 0.24 mmol in 100mL of benzene) under stirring. The second titration was also monitoredby removing small aliquots and analyzing them with SEC. After ˜2 equivof PBd⁻Li⁺ (0.48 mmol), relatively to DCMSDPE, had been added to thereactor, and when the end point was judged by SEC, the titration wasstopped. The second titration lasted about 24 hours, that is longer thanthe first one because the living polymer was a living star in this caseand not a linear branch and therefore the coupling reaction was slowerdue to the greater steric hindrance. The excess PBd⁻Li⁺ (˜0.12 mmol) wasremoved and kept for characterization and again the macromonomer wastransferred into another apparatus FIG. 18) were initially theappropriate amount of initiator s-BuLi (0.24 mmoles) was added. Thecolor immediately turned from deep yellow to deep red and after for 48hours under stirring a new amount of butadiene (1 g) was introduced. Analiquot was taken from the reactor for characterization and finallytrichlomethylsilane (0.06 mmol) was added. After the completion of thelinking reaction (˜30 days), the excess of the living species wasneutralized with degassed methanol, and the product was fractionated bythe toluene/methanol system. The fractionated G-3 dendritic copolymerwas precipitated into an excess of methanol and dried under vacuum,until constant weight. The molecular characterization results are givenin Table 6.

TABLE 6 M_(w) ^(b) Arm M_(w) ^(b) Arm M_(w) ^(b) Arm (G-3) (G-2) (G-1)M_(w) ^(c) Dendrite M_(w) ^(b) Dendrite (M_(w)/M_(n))^(a) Weight Sample(kg/mol) (kg/mol) (kg/mol) (kg/mol) (kg/mol) dendrite (g) 7 4.79 11.128.17 148.80 148.86 1.09 0.5 8 4.68 5.81 5.36 107.10 Klasm 9 7.66 7.7124.38 211.32 202.35 1.09 1 10 13.81 15.01 1.05 258.93 222.01 1.12 1113.81 18.06 ^(a)SEC in THF at 30° C., using PBd standards. ^(b)Obtainedby SEC-TALLS in THF at ^(c)Calculated from the molecular weights of thearms.

1. A convergent method for anionically synthesizing a highly branchedwell-defined 1^(st) generation polydiene comprising the following steps:reacting a diene monomer (d) with sec-diene-Li to form a singledouble-tailed macromonomer of (Pdd₁)⁻Li⁺, coupling two of said singledouble-tailed macromonomers of (Pdd₁)⁻Li⁺ together in a convergentmanner by reacting with dichloro methyl silane diphenylethylene(DCMSDPE) coupling agent to form a double macromonomer of polydiene witha middle active center, reacting said double macromonomer of polydienewith said diene monomer and sec-diene-Li at said middle active center toform a 1^(st) generation-diene-lithium branch on branch structure, andcombining three or more of said 1^(st) generation-diene-lithium branchon branch structures by reacting with trichloro silane coupling agent toform highly branched well-defined 1^(st) generation polydiene.
 2. Theconvergent method of claim 1 wherein said diene monomer is selected fromthe group consisting of butadiene, isoprene, 2-methyl-1,3-pentadiene,2-ethyl-1,3-pentadiene, 2-propyl-1,3-pentadiene, 2-butyl-1,3-pentadiene,2-pentyl-1,3-pentadiene, 2-hexyl-1,3-pentadiene, 2-ethyl-1,3-butadiene,2-propyl-1,3-butadiene, 2-butyl-1,3-butadiene, 2-pentyl-1,3-butadiene,2-hexyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene,2,3-diethyl-1,3-butadiene, 2,3-dipropyl-1,3-butadiene,2,3-dibutyl-1,3-butadiene, 2,3-dipentyl-1,3-butadiene,2,3-dihexyl-1,3-butadiene, myrcene (7-methyl-3-methylene-1,6-octadiene)and 1,3-cyclohexadiene.
 3. The convergent method of claim 2 furthercomprising a step of hydrogenating said highly branched well-defined1^(st) generation polydiene formed from said butadiene monomer to form ahighly branched well-defined 1^(st) generation polyethylene.
 4. Theconvergent method of claim 2 further comprising the step ofhydrogenating said highly branched well-defined 1^(st) generationpolydiene formed from said isoprene monomer to form a highly branchedwell-defined 1^(st) generation ethylene-propylene copolymer.
 5. Theconvergent method of claim 2 further comprising the step ofhydrogenating said highly branched well-defined 1^(st) generationpolydiene formed from said 2-methyl-1,3-pentadiene monomer to form ahighly branched well-defined 1^(st) generation atactic polypropylene. 6.A convergent method for anionically synthesizing a highly branchedwell-defined 2nd generation polydiene comprising the following steps:reacting diene monomer (d) with sec-diene-Li to form a singledouble-tailed macromonomer of (Pdd₁)⁻Li⁺, coupling two of said singledouble-tailed macromonomers of (Pdd₁)⁻Li⁺ together in a convergentmanner by reacting with dichloro methyl silane diphenylethylene(DCMSDPE) coupling agent to form a double macromonomer of polydiene witha middle active center, reacting said double macromonomer of polydienewith said diene monomer and sec-diene-Li at the middle active center toform a 1^(st) generation-diene-lithium branch on branch structure, andreacting said 1^(st) generation-diene-lithium branch on branchstructures with DCMCDPE coupling agent followed by the further additionof said single double-tailed macromonomer of (Pdd₁)⁻Li⁺ to form a highlybranched well-defined 2nd generation polydiene.
 7. The convergent methodof claim 6 wherein said diene monomer is selected from the groupconsisting of butadiene, isoprene, 2-methyl-1,3-pentadiene,2-ethyl-1,3-pentadiene, 2-propyl-1,3-pentadiene, 2-butyl-1,3-pentadiene,2-pentyl-1,3-pentadiene, 2-hexyl-1,3-pentadiene, 2-ethyl-1,3-butadiene,2-propyl-1,3-butadiene, 2-butyl-1,3-butadiene, 2-pentyl-1,3-butadiene,2-hexyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene,2,3-diethyl-1,3-butadiene, 2,3-dipropyl-1,3-butadiene,2,3-dibutyl-1,3-butadiene, 2,3-dipentyl-1,3-butadiene,2,3-dihexyl-1,3-butadiene, myrcene (7-methyl-3-methylene-1,6-octadiene)and 1,3-cyclohexadiene.
 8. The convergent method of claim 7 furthercomprising the step of hydrogenating said highly branched well-defined2^(nd) generation polydiene formed from said butadiene monomer to form ahighly branched well-defined 2nd generation polyethylene.
 9. Theconvergent method of claim 7 further comprising the step ofhydrogenating said highly branched well-defined 2^(nd) generationpolydiene formed from said isoprene monomer to form a highly branchedwell-defined 2nd generation ethylene-propylene copolymer.
 10. Theconvergent method of claim 7 further comprising the step ofhydrogenating said highly branched well-defined 2nd generation polydieneformed from said 2-methyl-1,3-pentadiene monomer to form a highlybranched well-defined 2^(nd) generation atactic polypropylene.